FUNCTIONALIZED BIOLOGICAL PRECURSORS OF TRICYCLIC TERPANES - INFORMATION FROM SULFUR-BOUND BIOMARKERS IN A PERMIAN TASMANITE

Desulfurization of the aromatic and polar maltene fractions of a tasma nite oil shale extract with Raney Ni yielded a series of tricyclic ter panes extending to C40. We suggest that the C40 homologs are derived f rom tetraterpenoid biological precursor(s) in the tasmanite, and were formed by biochemical cyclization of a C40 polyprenol. It is likely th at many of the lower carbon number tricyclic terpanes in these samples are early diagenetic alteration products of these C40 precursors. Tri cyclic terpane series in other samples that terminate at C30 or C45 (o r higher) could be derived from biochemical cyclization of other polyp renols of different lengths in related microbiota. The desulfurization products indicate that tricyclic terpanes in the tasmanite extract de rive from biological precursor(s) with functionalities in both the rin g system and the side chain. Novel desulfurization products included s ubstantial amounts of mono-unsaturated tricyclic terpenes (tentatively identified as 8,13-dimethyl-14-alkylpodocarp-13-enes, primarily C39) and a C21 acyclic isoprenoid, probably derived from the side chain of a C40 tricyclic terpenoid. These data suggest that phytane, and possib ly other isoprenoids in these samples, may partially derive from the s ide chain of lower-carbon-number tricyclic terpenoids.